What temp do they need in the winter?

Howdy! Hens in Montana. It gets a mite chilly here in the winter, so I am assuming I will need to monitor the temp in the coop. What's the low-tolerance inside temp for the hens? I found some thermostatically controlled outlets that turn on and off at various temps (35F/45F, 20F/30F, 0F/10F) and I can use either a ceramic heat bulb or a Sweeter Heater. I just want to know what the low end inside temp should be. Outside temps during the coldest part of the year will drop to daily highs around 0F and lows -20F, but never that cold for more than a few days at a time.

Lots of folks don't add any heat at all down below zero. If you have winter hardy breeds, your coop is free of drafts in winter, and chickens have access to unfrozen fresh water, then healthy adult birds can survive down to -20 and -30 even. Some do add lamps or other heat sources when temps get below zero, others below freezing. In your area, I'd go for one of the lower ranges of the plug in temp. regulators if you're going to use one. That way they get a bit of warmth, but are not shocked by the temp. difference of a "warm" coop inside, and severe outdoor temps.

I've used the regulated outlets for the past two winters, and love them. They even have them for hot/warm weather, for fans and such...

The problem I have with the heating the coop concept is both the price and the practicality. Solar would be great, but generating enough wattage to actually run heaters is tough. So, that leaves paying the power company. No can do. It would horrific to try and heat our barn. Secondly, how practical is it to raise the temperature any meaningful amount when it dips to -20? Even raising it to +10 would be difficult and again, horrifically expensive for the small amount of "help".

We had many, many nights that cold this past winter here in northern Michigan. The birds did just fine. Cozy, with deep straw bedding, dry, secure and they were just fine. All the popular cold hardy breeds were developed in New England and up state New York a century ago and well before Thomas Edison's invention. Chickens are kept in cold places such as Iceland, Norway, Finland and Russia, without heat, and have been for centuries.

Just as I think it would be difficult to keep a St Bernard dog in Florida. There are hundreds of BYC folk who keep chickens in northern climates successfully.

What I do is put hutches in my shed coop in the winter. I don't worry about the temp. inside the shed because they can crawl inside the two hutches (chick-n-hutch)- and get right under the 100 watt bulb.

So I run 200 watts in the winter when it gets below freezing.

Yes they can survive but I want them to be cozy. They are our pets.

I might add that I am prepared for (and set up for) putting them in our insulated garage in case of power outage so they don't freeze to death, being acclimated to heat.

A heated waterer is indispensable. Some use the rubber heated dog dishes but I like the plastic 3 gallon heater that can hang in the run. For winter here we put a light in the coop on a timer but that was a 13w efficiency light to promote egg laying. No real heat source and our girls did very well. Sure they are reluctant to come out of the coop when it's -15F but are quite comfortable at normal winter temps from 10F on up. What helps is to wrap/hang a tarp around the prevailing wind sides of your run.

I do not use heat lamps in my hen house. I live in Maine and our winters are long and cold.
I put plenty of hay in the house and my hens are just fine...they come out in the snow every day. It is hard to keep the water fresh tho. I just go out and change it when i can.